/*
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at 
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  
 */

using System;
using java = biz.ritter.javapi;

namespace org.apache.commons.collections
{

    /**
     * Defines an iterator that operates over a <code>Map</code>.
     * <p>
     * This iterator is a special version designed for maps. It can be more
     * efficient to use this rather than an entry set iterator where the option
     * is available, and it is certainly more convenient.
     * <p>
     * A map that provides this interface may not hold the data internally using
     * Map Entry objects, thus this interface can avoid lots of object creation.
     * <p>
     * In use, this iterator iterates through the keys in the map. After each call
     * to <code>next()</code>, the <code>getValue()</code> method provides direct
     * access to the value. The value can also be set using <code>setValue()</code>.
     * <pre>
     * MapIterator it = map.mapIterator();
     * while (it.hasNext()) {
     *   Object key = it.next();
     *   Object value = it.getValue();
     *   it.setValue(newValue);
     * }
     * </pre>
     *  
     * @since Commons Collections 3.0
     * @version $Revision$ $Date$
     *
     * @author Stephen Colebourne
     */
    public interface MapIterator : java.util.Iterator<Object>
    {

        /**
         * Checks to see if there are more entries still to be iterated.
         *
         * @return <code>true</code> if the iterator has more elements
         */
        //! we do not need declaration, because is in super type
        //bool hasNext();

        /**
         * Gets the next <em>key</em> from the <code>Map</code>.
         *
         * @return the next key in the iteration
         * @throws java.util.NoSuchElementException if the iteration is finished
         */
        //! we do not need declaration, because is in super type
        //Object next();

        //-----------------------------------------------------------------------
        /**
         * Gets the current key, which is the key returned by the last call
         * to <code>next()</code>.
         *
         * @return the current key
         * @throws IllegalStateException if <code>next()</code> has not yet been called
         */
        Object getKey();

        /**
         * Gets the current value, which is the value associated with the last key
         * returned by <code>next()</code>.
         *
         * @return the current value
         * @throws IllegalStateException if <code>next()</code> has not yet been called
         */
        Object getValue();

        //-----------------------------------------------------------------------
        /**
         * Removes the last returned key from the underlying <code>Map</code> (optional operation).
         * <p>
         * This method can be called once per call to <code>next()</code>.
         *
         * @throws UnsupportedOperationException if remove is not supported by the map
         * @throws IllegalStateException if <code>next()</code> has not yet been called
         * @throws IllegalStateException if <code>remove()</code> has already been called
         *  since the last call to <code>next()</code>
         */
        //! we do not need declaration, because is in super type
        //void remove();

        /**
         * Sets the value associated with the current key (optional operation).
         *
         * @param value  the new value
         * @return the previous value
         * @throws UnsupportedOperationException if setValue is not supported by the map
         * @throws IllegalStateException if <code>next()</code> has not yet been called
         * @throws IllegalStateException if <code>remove()</code> has been called since the
         *  last call to <code>next()</code>
         */
        Object setValue(Object value);

    }
}